There are four major methods: dye testing, television inspection, smoke testing and flow monitoring.
By flushing water and clothing dye into a suspicious downspout or sump pump, MSD can determine sources of clear water entering the sewers by the color of the water as it flows through the pipes.
By guiding portable television cameras through the sewer pipes, MSD can detect many of the sources of clear water entering the sewers.
By filling the sanitary sewer line with smoke and watching where it emerges, MSD can detect many more sources of clear water. The smoke is kept from entering buildings by the drain traps required on all sanitary fixtures and drains. It will emerge from the sewer stand-pipe vents on the roof of buildings and from improper connections such as downspouts. It may also emerge from holes in the ground that lead to leaks in sewer lines.
By inserting special measuring devices into the sewer lines, MSD crews can monitor the water flowing through them. If the flow increases during rainstorms, it's a sure sign of infiltration.
What happens when you detect a leak or an improper connection?
If the leak is in the public sewer line, MSD will repair it.
If the source of the clear water is in a private line entering the public sewer, MSD will notify the property owner. The property owner should consult with a licensed plumber to determine the source of the inflow or infiltration and to have the problem corrected.
MSD will conduct a follow-up inspection. If the problem has not been corrected, the property owner and the state plumbing inspector will be notified by MSD. This could result in further investigation as a violation of the Kentucky State Plumbing Code and MSD's Wastewater / Stormwater Discharge Regulations.
What can a property owner do to minimize basement sewer backups?
MSD does not recommend the use of blow-up or expansion type pipe plugs for drains. The pressure in the sewer pipe can blow them out.
I've never had basement flooding due to a sewer backup. Why should I remove my improper connections?
If your plumbing pumps or drains clear water into the sanitary sewer, it may well be the cause of flooding in your neighbor's basement. It may also cause the sewer to overflow, polluting the storm drains and streams.
Does the requirement to remove improper connections pertain only to certain sewer service areas?
No. U.S. Environmental Protection Agency regulations require MSD, as well as other local governments and independent authorities, to stop the intrusion of clear water into all sanitary sewers.
Some old neighborhoods, however, have "combined" sewers, where sanitary sewage and stormwater are handled together. These systems were built in the days before sewage treatment plants, when all the water was dumped into the streams and rivers, causing tremendous pollution problems. Today, all the combined MSD sewers flow into sewage treatment plants, where they still create problems during heavy rains. Under new Environmental Protection Agency regulations, these problems also must be solved. MSD is now implementing a plan to correct the problems associated with combined sewers in our older neighborhoods.
February 28, 2012